Oil filters



Dec. 27, 1966 q E. RQSAEN ETAL 3,294,238

OIL FILTERS Original Filed May 2. 1960 2 Sheets-Sheet 1 INVENTORS OSCARE.ROSAEN NILS O.'ROSAEN W MMV ATTORNEYS Dec. 27, 1966 Original Filed May2. 1960 FILTER IS CLEAN O E. ROSA EN ETAL OIL'FILTERS 2 Sheets-Sheet 2CLEANING FILTER NEEDS INVENTORS OSCAR E ROSAEN NILS O.ROSAEN ATTORNEYSUnited States Patent C) 3,294,238 OIL FILTERS Oscar E. Rosaen, GrossePoint, and Nils S. Rosaeu,

Bloomfield Hills, Mich., assignors to The Rosaen Filter Company, HazelPark, Mich., a corporation of Michigan Continuation of application- Ser.No. 26,046, May 2, 1960.

This application Dec. 11, 1963, Ser. No. 331,640 3 Claims. (Cl. 210-90)This application is a continuation of our copending application SerialNo. 26,046, filed May 2, 1960, and now abandoned.

The present invention relates to fluid filters and in particular toimprovements in oil filters of the type used for filtering circulatingoil as commonly used in many hydraulically actuated industrialoperations.

Such operations generally employ a fluid pump drawing oil from a sourceof supply and delivering the same under pressure throughout the fluidsystem for the operation of suitable component parts thereof, afterwhich the fluid is returned to the source of supply to be recirculatedby the pump. Filters are generally installed in such systems between thesource of supply and the intake to the pump so that dirt, grit and thelike foreign matter are removed from the oil to prevent such matter fromfouling the pump and other parts of the system.

In such systems, when the filter begins to become clogged with foreignmatter screened from the fluid, such clogging, with consequent reducedoil flow, is difficult to detect before the system to which the oil issupplied becomes starved or receives less oil than is desirable forproper operation and protection of the system.

Among the objects of the present invention is to provide a filter which,when it becomes clogged from continued use, will by-pass oil to preventinterference with the operation of the system due to lack of oil.

Another object of the invention is to provide a filter device which willindicate and signal the clogging of the filter element before it reachesan undesirable extent.

Another object is to provide a filter which will bypass the oil when theclogging becomes excessive and when and if the signal is not observed oris completely ignored, to thereby protect the system and prevent seriousdamage to the pumps and other components of the system.

Another object of the invention is to provide a filter device forhydraulic systems with by-pass means for bypassing the fluid around thefiltering element when the element becomes excessively clogged withfiltered dirt, and in which device provision is made for clearlyindicating to an attendant the precise condition of the filter elementat any time and which indicating means will clearly signal the need forchanging the filter element before actual by-passing of the fluidocours.

Another object of the invention is the provision of an accurate andsimplified indicating means for signalling the condition of the filterat all times.

A further and important object of the invention is to provide a filterwhich, when by-passing, causes the oil flow to traverse a fresh screenso that no unfiltered oil will pass into the system.

Other objects and advantages will readily occur to those skilled in theart upon reference to the following description and the accompanyingdrawings in which FIG. 1 is a longitudinal sectional view taken on line11 of FIG. 2 showing the preferred form of the present invention;

FIG. 2 is a top plan view of the oil filter shown in FIG. 1, with partsbroken away and shown in section to show the mechanism for actuating theindicating arm in relation to the filter element;

3,294,238 Patented Dec. 27, 1966 ice FIG. 3 is a fragmentary sideelevation showing the indicating means and the legend plate; and

FIG. 4 is a perspective view of the indicating arm mechanism completelyremoved from the filter housing.

The present oil filter is similar in certain basic aspects to the oilfilter shown and claimed in our copending prior application Serial No.649,059, filed March 28, 1957, now Patent No. 3,053,389, issuedSeptember 11, 1962, but differs from the structure there shown in themeans for indicating movement of the filter element in the housing, aswell as in the novel provision of a secondary screen associated in thefilter element assembly.

Filters of the present type are commonly referred to as suction filters,since they are installed on the suction or intake side of the pump, withthe outlet of the filter unit connected to the intake of the pump andthe inlet of the filter unit connected to a conduit leading from the oilreservoir or supply of the hydraulic system. When the pump is inoperation, fluid is drawn from the supply through the filter unit to thepump which in turn delivers the fluid under pressure to the system foractuation of the components thereof, after which the fluid is returnedto the reservoir or supply for recirculation. In the accompanyingdrawings the system, pump and oil supply are not shown, since it isbelieved such a showing is not necessary for an adequate understandingof the invention to those skilled in the art.

Referring to FIG. 1 of the drawings, it will be seen that the presentoil filter comprises a generally cylindrical housing provided near oneend with a lateral boss through which is arranged the inlet 111. At thesame end is provided an axially arranged outlet 112. The other end ofthe housing 110 is closed by a suitable cover or closure plate removablysecured to the housing by suitable bolts as shown, said closure plateproviding when removed from said housing access to the interior of thehousing for the removal and insertion of the filter element.

Inside of the housing and coaxial with the outlet 112 the housing wallis finished to provide a cylinder 116 adapted to receive a cooperatingpiston 117 in the form of an annulus. Carried by the piston 117 andcoaxial tliarewith is a cylindrical screen or filtering element 120,seated upon a suitable shoulder 121 surrounding the opening 122 in thepiston annulus.

At the other end of the housing, the closure plate 115 is provided onits inner face with a cylindrical boss 125 terminating in spaced tongues12 6. The boss 125 is coaxial with cylinder 116 and of smaller diameter,and serves as a guide for a ring 127, provided on its outer peripherywith a deep flange 128, within which is seated the end of screen 120.Ring 127 is formed to have an inner diameter such as to closely fit theboss 125 but slide freely thereon.

Also shown in connection with this invention is the employment of asecond concentrically arranged screen or filtering element 131 which isadapted to filter the fluid only when the fluid is being by-passed ofthe main screen or filter element 120, as will hereinafter be explained.Mounted on ring 127, and abutting the end of screen 120, is an annularplate 130 which has fixed to its inner edge portion the second screen131 closed at its free end, the ring 127 with screens 120 and 131 beingfixed together as a unit by means of suitable screws or bolts 132passing through ring 127 and threaded into piston 117 as shown.

The assembly of piston, screens and ring is maintained in the positionshown in FIG. 1, ie with the ring 127 at the base of the boss 125against the closure 115, by means of a selected coil spring seatedagainst a shoul- 3 der in the end of cylinder 116 and on a suitableshoulder 141 formed in the piston.

On one side of the housing is provided a flat, preferably rectangular,boss 150, see FIGS. 2 and 3, having near one end an opening through theboss and housing wall and acting as a bearing for a short shaft 151carrying at its inner end a crank arm 152 and on its outer end anindicator hand 153. The free end of the .crank arm is positioned withits outer end arranged to bear against the flange 128 of ring 127 to beactuated thereby on axial movement to the left of the filter elementassembly or cartridge, which will result in partial rotation of the hand153 over suitable indicia 154, thus indicating to the attendant from thehand position the condition of the filter screen or element.

As shown in FIG. 3, the indicia 154 preferably contains such legends asFILTER IS CLEAN, FILTER NEEDS CLEANING and BY-PASSING. The indicator arm153 is adjusted on the shaft 151 with reference to the crank arm 152, sothat arm 153 points to the FILTER IS CLEAN position when the outer endof the crank arm is hearing against the flange 128 with the ring 127being firmly held against the closure plate 115 by coil spring 140.

The compression spring 140 is selected of a strength sufficient toretain the filter element 120 together with its associated end caps,piston 117 and ring 127, when the screen is clean, in the extreme righthand position of the casing as viewed in FIG. 1. The spring selectionwill, of course, be based upon the rating of the pump in the particularsystem in which the filter unit is being installed, consideration beinggiven to the desired permissible pressure drop between the inlet 111 andthe outlet 112 of the unit when the pump and system are in operation.

In the operation of the device, oil is drawn in through the inlet 111through suction applied by the pump in the line connected to the outlet112 filling the outer chamber surrounding the screen 120 and flowsnormally through the screen 120 to the interior thereof where it passesthrough the opening 122 and out to the intake of the pump. It will beappreciated that in addition to filling the chamber outside of saidscreen 120, the oil will normally enter between the abutting faces ofthe ring 127 and the closure plate 115, but will not pass between theclosely fitting surfaces defining the ring opening and boss 125.However, as heretofore mentioned, the selected spring 140 will preventthe cartridge from moving to the left away from the face of the closureplate under normal operating conditions.

As the screen 120 begins to become clogged and the pressure differencebetween inlet and outlet rises above the selected or predeterminedpermissible pressure drop, the piston, screen and ring assembly beginsto move against the resistance of spring 140 until the ring 127eventually clears the boss 125, allowing at that time oil to by-passscreen 120 and flow directly to the interior between the boss extensions126. However, the fluid by-passing the filtering screen 120 will also bescreened or filtered since it must pass through the secondary screen 131before reaching outlet 112 on its way to the pump intake. Under thesecircumstances it will be seen that no dirty oil can pass out of theoutlet 112 as it must pass through the fresh secondary screen 131.Screen 131 may be of the same mesh as screen 120 but is preferablyformed of a somewhat coarser mesh material.

It will thus be apparent that movement of the filter cartridge assemblyto the left as viewed in FIG. 1 due to an increase in pressuredifferential does not uncover any additional areas to pressure, sincethe piston 117 is at all times piloted within the cylinder 116 and theopening in ring 127 is at all times piloted on the guide boss 125.Operating pressure differential occurs substantially only between theinner and the outer faces of the ring 127. Hence the filter element actsas a true piston, as opposed to conventional poppet valve devices, andbeing urged to the right by the spring 140, the filter assembly will,after it starts to move tend to assume a position where spring pressureis balanced by fluid pressure forces. The greater the fluid pressuredifferential caused by clogging of the screen, the greater thecompression of the spring 140. The degree of movement of the filtertoward the by-pass position is thus a linear function of pressure dropacross the filter screen.

As the filter element gradually moves toward the outlet end of thecasing in response to the differential pressures involved as progressiveclogging of the filter continues, flange 128 of the ring or cap 127 willmove the crank arm 152, as indicated by the dotted line position shownin FIG. 2, which will in turn rotate the indicator arm 153 from theFILTER IS CLEAN position downwardly, as viewed in FIG. 3, to indicatethe filter needs to be cleaned or changed for a new filter andeventually to the BY-PASSING position when by-passing is in progress. Itwill be noted that there is a relatively long or extended movement ofthe ring 127 between the time it begins to leave the adjacent wall ofclosure plate and the time it exposes the openings between the tongues126 on boss to the incoming oil or fluid. There is consequently acontinued and adequate signal being given the attendant throughout thisentire range of movement of the filter element so that the precisecondition of the filter screen is known to the attendant at any momentof operation and long prior to actual by-passing of the screen 120.

Whenever a clean filter element is inserted into the filter housing andprior to resumption of operation of the system, the operator should movethe indicator arm 153 to the FILTER IS CLEAN position on the legendplate which will bring the crank arm against the flange of ring or cap127. As the clogging of the filter progresses, the hand 153 will bemoved as described above. If the filter screen has become progressivelyclogged to the point where the cartridge has moved the hand to theFILTER NEEDS CLEANING position and this forewarning has gone unheeded bythe operator prior to shutting down the system and the pump, it will benoted that the arm will remain in that indicating position even thoughthe system is idle, thus forewarning the operator prior to resumption ofoperation of the system that the filter is dirty and should be changedbefore operation begins.

In addition to the indication given by the arm 153, there is likewise asecondary indicating means, namely, a sight glass located in the wall ofthe housing so that an observer may note the position of the ring 127with relation to the clean now marking, as shown in FIG. 2.

While the present invention has been explained and described withreference to specific embodiments of structure, it will be understood,nevertheless, that numerous modifications and variations are susceptibleof being incorporated without departure from the essential spirit orscope thereof. Accordingly, it is not intended for an understanding ofthis invention to be limited by the foregoing description nor by theillustrations in the annexed drawings, except as indicated in thehereinafter appended claims.

We claim:

1. An oil filter comprising a cylindrical housing, a laterally arrangedoil inlet thereto, an axially arranged oil outlet therefrom, the housingwall surrounding said outlet being finished to provide a cylinder, anannular piston slidable in said cylinder and carrying one end of a firstcylindrical screen surrounding the opening in the annular piston andspaced from the wall of the housing, a ring abutting the other end ofsaid screen and fixed thereto, a second cylindrical screen fixed at oneend thereof to said ring and closed at the opposite end andconcentrically disposed within and spaced from the first screen to forma two screen cartridge unit, a closure plate for said housing at the endopposite said outlet, said plate having a boss coaxial with said ringand slidably fitting therein, spring means biased between said pistonand said housing at the end of said housing opposite said ring formaintaining the piston, screen and ring assembly against said closureplate and with said boss closing the ring opening, said spring meansallowing the said assembly to move axially away from said plate anduncover the ring opening to permit incoming oil to enter said openingand by-pass said first mentioned screen when the pressure differentialbetween the space inside and outside said screens increases beyond apredetermined amount due to clogging of the first screen, and meansengaging the ring and movable thereby upon axial movement of saidassembly to indicate the extent of said movement.

2. The filter as defined in claim 1 and in which said last mentionedmeans comprises an indicating arm rotatably mounted on the side of saidhousing and carried by a shaft extending through the housingtransversely to the direction of movement of said assembly, a crank armcarried by the inner end of said shaft with the free end of said crankarm curved and positioned adjacent to and engageable by said ring formoving said indicating arm on movement of said assembly and suitableindicia carried by said housing and correlated with respect to saidindicator arm to indicate the extent of the axial movement of saidassembly to thereby indicate the condition of the first screen and whenby-passing of the first screen is produced.

3. A fluid filter comprising a housing, an inlet thereto, an outlettherefrom disposed at one end of said housing, the housing wallsurrounding said outlet being finished to provide a guide surface, apiston having a central opening and slidable along said guide surface,said piston carrying one end of a first hollow screen surrounding theopening in the piston and spaced from the wall or" the housing, a ringabutting the other end of said screen and fixed thereto, a second hollowscreen fixed at one end thereof to said ring and closed at the oppositeend and disposed within and spaced from the first screen to form a twoscreen cartridge unit, a closure plate for said housing at the endopposite said outlet, said plate having a boss coaxial with said ringand slidably fitting therein, spring means biased between said pistonand said housing at the end of said housing opposite said ring formaintaining the piston, screen and ring assembly against said closureplate and with said boss closing the ring opening, said spring meansallowing the said assembly to move axially away from said plate anduncover the ring opening to permit incoming fluid to enter said openingand by-pass said first mentioned screen when the pressure differentialbetween the space inside and outside said screens increases beyond apredetermined amount due to clogging of the first screen, and meansengaging the ring and movable thereby upon axial movement of saidassembly to indicate the extent of said movement.

References Cited by the Examiner UNITED STATES PATENTS 2,998,138 8/1961Mould et al. 210-132 X 3,000,505 9/1961 Scavuzzo 210-432 3,076,3352/1963 Rosaen 210- X 3,157,596 11/1964 Rosaen 210-90 REUBEN FRIEDMAN,Primary Examiner.

SAMIH N. ZAHARNA, Assistant Examiner.

